Why is my phone bootloader unlocked?

The QCA U/U1 bootloader is permanently locked, and CANNOT BE bootloader unlocked; only the parallel market versions with the Exynos (F series) chip are unlockable. See my old Pixel 7 vs. this U1 A42 5G as to how you can tell a US U/U1 vs. a parallel import variant (my P8 is the same as the P7):

Now for the worst way to block it (VZW P3a):

Where did you purchase this device exactly? New or used? If you bought the phone used, it was imported by the previous owner for bootloader unlocking purposes. Once the deed is done on Samsung devices, it's DONE; you can't relock it like with unlocked Pixels. Motorola is much the same. You can't relock it or use S Health on some newer phones. What happened was someone did that to install a custom ROM like LineageOS, for example; on US-bound devices, the bootloader is locked on both the U/U1 (Factory unlocked) devices because Samsung refuses to flip a switch to allow us to bootloader unlock the U1 phones, which became the norm with the S10; the S1-S7 didn't have issues, but the S8-S9 are unknown to me; it may be like the S1-S7.

This isn't much of a security risk for much of anything. I wouldn't be afraid to use an unlocked bootloader device daily, especially if it had a well-written custom ROM like LineageOS. Some even auto-relock the bootloader on Pixel devices, but it's a permanent, one-way switch due to how Motorola and Samsung handle it. You have to have physical access to the phone to flash ROMs using a computer. I can't stand Samsung for repair cost issues, but I'd risk paying nearly $200 for a screen to have a Samsung like this all day long and ACTUALLY repair it.